The present invention relates to new methods of manufacturing benzoquinoline inhibitors of vesicular monoamine transporter 2 (VMAT2), and intermediates thereof. Novel methods of manufacturing benzoquinoline compounds of formula (I), including tetrabenazine and deuterated tetrabenazine analogs such as d6-tetrabenazine are disclosed herein. Tetrabenazine is a vesicular monoamine transporter 2 (VMAT2) inhibitor and is commonly prescribed for the treatment of Huntington's disease. d6-Tetrabenazine is a deuterated analog of tetrabenazine which has improved pharmacokinetic properties when compared to the non-deuterated drug and is currently under clinical development.
